1. Field of the Invention
The present invention relates to an alternating current plane discharge type plasma display panel and, more particularly, it relates to an alternating current plane discharge type plasma display panel having structurally improved plane electrodes.
2. Description of the Related Art
Plasma display panels (to be referred to as PDPs hereinafter) are known and designed to display images by causing electrons accelerated by an electric field to collide with and excite discharge gas and transforming ultraviolet rays emitted by way of a relaxation process into rays of visible light. Such PDPs are normally provided as flat surface image display devices having a large display screen and a large capacity. Particularly, alternating current (to be referred to as AC hereinafter) discharge type PDPs are advantageous in comparison with direct current (to be referred to as DC hereinafter) discharge type PDPs in terms of luminance of emitted light, efficiency of light emission and service life.
Japanese Patent Laid-Open Publication No. Hei. 8-22772 discloses an AC plane discharge type PDP of the type under consideration. FIG. 1 of the accompanying drawings is a partly cut out schematic perspective view of a PDP similar to the one illustrated in FIG. 1 of the above cited publication. FIG. 2A is a schematic plan view of plane electrodes of the PDP similar to those illustrated in FIG. 2 of the above cited publication. FIG. 2B is a schematic cross sectional view of one of the plane electrodes. FIG. 3A is a schematic plan view of plane electrodes similar to those illustrated in FIG. 8 of the above cited publication. FIG. 3B is a schematic cross sectional view of one of the plane electrodes. FIG. 4A is a schematic plan view of plane electrodes similar to those illustrated in FIG. 11 of the above cited publication. FIG. 4B is a schematic cross sectional view of one of the plane electrodes. The structure of the known PDP will be described below with reference to these drawings.
As far as this specification is concerned, a xe2x80x9cvertical directionxe2x80x9d and a xe2x80x9chorizontal directionxe2x80x9d correspond to the column direction and the row direction respectively of the plane electrodes of the plasma display device that is typically fitted to a wall surface for use, respectively. The expressions of xe2x80x9clongitudinal directionxe2x80x9d and xe2x80x9ctransversal directionxe2x80x9d may sometimes be used in place of xe2x80x9cvertical directionxe2x80x9d and xe2x80x9chorizontal directionxe2x80x9d, respectively, in the following description. The expressions of xe2x80x9cupwardxe2x80x9d and xe2x80x9cdownwardxe2x80x9d refer to those directions viewed along the thickness of the glass substrate and along the layers thereon, respectively. More specifically, xe2x80x9cupwardxe2x80x9d refers to the direction in which layers are formed sequentially on the glass substrate in the manufacturing process. A common electrode may also be referred to as a sustenance electrode. A line electrode may also be referred to as a bus electrode or trace electrode.
A plurality of data electrodes 2 typically made of silver (Ag) are formed longitudinally (in the column direction) to run along the longitudinal central axes of the cells on a back substrate 1 typically made of soda-lime glass. A white dielectric layer 3 made of PbO (lead oxide), SiO2 (silicon oxide), B2O3 (boron oxide), TiO2 (titanium oxide) or ZrO2 (zirconium oxide) is arranged on the data electrodes 2. Then, a plurality of partition walls 4a typically made of PbO, SiO2, B2O3, TiO2, ZrO2 or Al2O3 are formed on the white dielectric layer 3 and run longitudinally in parallel with the data electrodes 2. Fluorescent layers 5 that are adapted to emit visible rays of light of red, green and blue (fluorescent layers 5a for red cells, fluorescent layers 5b for green cells, fluorescent layers 5c for blue cells) are arranged alternately on the white dielectric layer 3 including the lateral surfaces of the partition walls 4a. 
A plurality of plane electrodes 7a typically made of SnO2 (tin oxide) or ITO (indium tin oxide) are formed on the bottom surface of a front substrate 6 typically made of soda-lime glass so that each one crosses the corresponding transversal central axes of the cells. More specifically, plane electrodes 7a are arranged in the transversal direction (in rows) and in the longitudinal direction (in columns). Narrow strip-shaped trace electrodes 8a typically made of silver (Ag) are formed under the plane electrodes 7a and run transversally in a direction perpendicular to the data electrodes 2. The trace electrodes 8a are provided in pairs. The plane electrodes 7a corresponding to each pair of trace electrodes 8a are electrically connected to the latter to form a scan electrode 9a and a common electrode 10a that run transversally (in the row direction). The resulting scan electrodes group and the common electrodes group are arranged alternately in the longitudinal direction (column direction). A transparent dielectric layer 11 typically made of PbO, SiO2 or B2O3 is formed under the scan electrodes 9a and the common electrodes 10a and then a protection layer 12 typically made of MgO (magnesium oxide) is formed under the transparent dielectric layer 11.
Then, the back substrate 1 and the front substrate 6 are bonded to each other with the layered structures facing each other and the entire device is air-tightly sealed by means of frit glass arranged along the peripheral edges of the substrates. The device contains therein a discharge gas such as He (helium), Ne (neon), Ar (argon), Kr (krypton) or Xe (xenon) for generating ultraviolet rays to show a predetermined internal pressure level.
A visible light reflecting layer containing TiO2, ZrO2 or the like may be arranged under the fluorescent layer 5 on the back substrate 1 in order to improve the luminance of emitted light. Similarly, colored layers corresponding to the red cells, the green cells and the blue cells may be arranged in the transparent dielectric layer 11 in order to improve the color temperature and the color purity.
Now, the operation of the PDP having the above described configuration will be described below. The data electrodes 2 to which a signal voltage pulse is applied independently on a line by line basis and the scan electrodes 9a to which a scan voltage pulse is applied sequentially on a line by line basis are made to electrically discharge oppositely for writing discharges. This is done in order to generate wall charges and priming particles (electrons, ions, meta-stable particles, etc.) and select cells. Then, the scan electrodes 9a to which a sustained voltage pulse is applied after the application of the scan voltage pulse and the common electrodes 10a are made to give rise to sustaining discharges that are plane discharges. This is done in order to cause the fluorescent layer 5 to emit visible light and make the cells operate for displaying an image.
The known arrangement of electrodes described above and illustrated in FIGS. 2A and 2B is adapted to provide each cell (unitary light emitting pixel) with a plane electrode 7a to reduce the surface area of the plane electrodes 7a as a whole and also with a sustaining discharge current. The light emitting efficiency of the panel is maximized while the sustained voltage is reduced to by turn lower the power consumption rate by optimizing a length L1 and a width W1 of the plane electrode. As a result, the temperature rise of the panel in operation is suppressed to improve the reliability of operation of the panel.
Referring to FIGS. 3A and 3B, or FIGS. 4A and 4B showing alternative known arrangements of electrodes, the plane electrodes 7b and 7c are provided with narrow sections 13a and 13b respectively to further reduce the surface area of the plane electrodes 7b and 7c as a whole and lower the sustaining discharge current. As a result, the power consumption rate of either arrangement of FIGS. 3A and 3B or FIGS. 4A and 4B is reduced from that of the arrangement of FIGS. 2A and 2B so that the temperature rise of the panel in operation is further suppressed.
Particularly, in the case of the plane electrodes 7b shown in FIGS. 3A and 3B and the plane electrodes 7c shown in FIGS. 4A and 4B, it is possible to produce preliminary discharge plasma on a stable basis only in limited areas located near the plane discharging gaps when the device is operating for preliminary discharges (plane discharges for reducing the variances in the operating performance among the cells). Thus, it is possible to increase the difference between the intensity of emission of visible light of the preliminary discharge phase and that of the sustaining discharge phase to consequently improve the contrast of the displayed image if compared with the arrangement of the plane electrodes 7a without such narrow sections 13a and 13b. 
Meanwhile, Japanese Patent Laid-Open Publication No. 2000-156167 discloses an AC drive plane discharge type plasma display panel including a pair of transparent plane electrodes (including a scan electrode and a common electrode) disposed to face via a discharging gap located between them and provided with a plurality of micro-holes. Additionally, the publication describes that, by providing the transparent plane electrodes with such micro-holes, any possible increase in the current density that can occur when the dielectric layer is made thinner to reduce the operating voltage can be prevented from taking place. This consequently secures a light emitting efficiency and a service life of the AC-PDP. However, the above described prior art is accompanied by the following problems. Firstly, while the known structural arrangement shown in FIGS. 2A and 2B provides a high luminance of emitted light, it entails a low light emitting efficiency and a large operating load as well as a poor performance in terms of transition from writing discharges (selecting operation) to sustaining discharges (display operation) and a large discharge interference.
FIG. 2B is a schematic cross sectional view taken along line Axe2x80x94A in FIG. 2A. Referring to FIG. 2B, the ultraviolet rays 14 generating region that is effectively utilized for transforming UV rays into rays of visible light in the fluorescent layer 5 is an outer region 15a of the sustaining discharge plasma (or the region located outside the broken line shown in FIG. 2B). In other words, an inner region 16a of the sustaining discharge plasma (or the region located inside the broken line in FIG. 2B) simply wastes power. With the known structural arrangement of FIG. 2B, while sustaining discharge plasma expands to all the cells and hence the luminance of emitted light is raised because the fluorescent layer 5 is irradiated with ultraviolet rays 14 over a wide area, power is lost to a large extent to lower the light emitting efficiency. At the same time an inutile inner region 16a that is not effectively used for transforming ultraviolet rays into rays of visible light also expands. A poor light emitting efficiency means a high power consumption rate for the display operation.
For the cell selecting operation and the display operation, the plane electrodes 7a do not necessarily need to be uniformly arranged over all the cells. The plane electrodes are required to effectively expand sustaining discharge plasma without adversely affecting the transition from writing discharges to sustaining discharges. Therefore, the plane electrodes need to be designed to meet this requirement in order to maximize the efficiency of operation. However, with the known structural arrangement of FIGS. 2A and 2B where the plane electrodes 7a are arranged over all the cells, the plane electrodes 7a and the data electrodes 2 show a high degree of inutile capacity coupling. This gives rise to a large operating load for electrically charging the capacities. As the inutile capacity coupling increases, a large amount of power needs to be consumed when charging the capacities and the waveform of the voltage pulse may be deformed to degrade the display performance of the panel.
Additionally, as for the transition from writing discharges to sustaining discharges, it is very important to generate wall charges highly densely near the plane discharging gaps, particularly on the longitudinal central axes of the cells (or on the data electrodes 2) on the plane electrodes. However, with the known structural arrangement of FIGS. 2A and 2B where the plane electrodes 7a are formed extensively over the data electrodes 2, writing discharges occur in a scattered manner over a large area. This generates a poor distribution pattern of wall charges that are formed by writing discharges. When wall charges formed by writing discharges show a poor distribution pattern, in addition to the deterioration of the transition to sustaining discharges, cells that are arranged adjacently in the longitudinal and transversal directions can give rise to discharge interferences so that error ONs and error OFFs can occur with the cells. Then, the device is forced to operate only with a narrow margin.
The wall charges that are generated by sustaining discharges do not need to show a uniform distribution pattern over all the cells. However, with the known structural arrangement of FIGS. 2A and 2B where the plane electrodes 7a are formed extensively over all the cells, strong sustaining discharges can spread over all the cells so that the wall charges formed by sustaining discharges show a widely spread distribution pattern. Particularly when wall charges are produced densely close to non-discharging gaps, the power consumption rate rises remarkably due to writing discharges, sustaining discharges and preliminary discharges and it becomes no longer possible to cancel the unnecessary wall charges on the plane electrodes 7a by preliminary discharges. Then, as pointed out above, cells that are arranged adjacently in the longitudinal and transversal directions can give rise to discharge interferences so that error ONs and error OFFs can occur with the cells. Thus, the device is forced to operate only with a narrow margin.
If the length L1 and the width W1 of the plane electrodes are reduced in an attempt for solving the above problem, new problems including a lowered luminance of emitted light and a high sustained voltage will occur.
While the known structural arrangement of electrodes shown in FIGS. 3A and 3B provides a high light emitting efficiency, a good performance for transition from writing discharges to sustaining discharges and scarce discharge interferences, it is accompanied by the problems of a low luminance of emitted light and a large operation load.
FIG. 3B is a schematic cross sectional view taken along line Bxe2x80x94B in FIG. 3A. The luminance of emitted light of the PDP that is observed is that of light produced by the fluorescent layer 5 as a result of transformation from ultraviolet rays into rays of visible light. Therefore, preferably the fluorescent layer 5 is irradiated extensively with ultraviolet rays 14 until the capacity of the fluorescent layer 5 for transforming ultraviolet rays into rays of visible light is saturated for the purpose of achieving a high luminance of emitted light. However, with the known structural arrangement of electrodes shown in FIGS. 3A and 3B, sustaining discharge plasma is contracted to reduce its volume along the narrowed sections 13a formed on the longitudinal central axes of the cells (or on the data electrodes 2). As the volume of sustaining discharge plasma is reduced, the rate of generation of the ultraviolet rays 14 is also reduced to make it no longer possible to irradiate extensively the fluorescent layer 5 with ultraviolet rays 14. Then, the luminance of emitted light is reduced because the rate at which ultraviolet rays are transformed into rays of visible light is lowered.
Furthermore, referring to FIG. 3B, as the distance separating the outer region 15b of the sustaining discharge plasma and the fluorescent layer 5 is increased, of the ultraviolet rays including those (resonance beams: wavelength of 147 nm) emitted from excited Xe atoms and those (molecular beams: wavelength of 172 nm) emitted from excited Xe molecules, which are typical sources of ultraviolet rays 14, only resonance beams are utilized with a poor efficiency to by turn reduce the rate at which the fluorescent layer 5 transforms ultraviolet rays into rays of visible light. The reason for this is that, since resonance beams reach the fluorescent layer 5 and repeat the process of resonance absorption/relaxation radiation with Xe atoms in a ground state, there is high probability that the sustaining discharge plasma will lose energy for irradiating ultraviolet rays 14 on the way. This is due to the effect of ionization due to collisions of electrons and ions when the outer region 15b of the sustaining discharge plasma and the fluorescent layer 5 are separated from each other by a long distance. It should be noted that the light emitting efficiency of the known electrode arrangement of FIGS. 3A and 3B is higher than that of the known electrode arrangement of FIGS. 2A and 2B because the inner region 16b of sustaining discharge plasma that wastes power is smaller in the former.
Still additionally, with the known structural arrangement of electrodes shown in FIGS. 3A and 3B, the plane electrodes 7b are formed only near the plane discharging gaps and on the longitudinal central axes of the cells (or on the data electrodes 2). With such an arrangement, while the wall charges formed by writing discharges and sustaining discharges show a good distribution pattern and the transition from writing discharges to sustaining discharges operate well to reduce discharge interferences, a large inutile capacity coupling remains between the plane electrodes 7b and the data electrodes 2. This makes an operating load for electrically charging the capacities larger. As pointed out earlier, when the inutile capacity coupling is large, a large amount of power needs to be consumed when charging the capacities and the waveform of the voltage pulse may be deformed to degrade the display performance of the panel. If the width W2 of the plane electrodes is reduced in an attempt for solving the above problem, new problems including a lowered luminance of emitted light and a rise in both the writing voltage and the sustained voltage will occur. If the length L2 of the plane electrodes is increased, a reduction in the contrast of the displayed image will occur and the distribution of the wall charges will deteriorate.
Now, while the known structural arrangement of electrodes shown in FIGS. 4A and 4B provides a high luminance of emitted light, a high light emitting efficiency and a low operation load, it is accompanied by the problems of a poor performance for transition from writing discharges to sustaining discharges and frequent discharge interferences.
FIG. 4B is a schematic cross sectional view taken along line Cxe2x80x94C in FIG. 4A. With the known structural arrangement of electrodes shown in FIGS. 4A and 4B, sustaining discharge plasma can easily expand over all the cells along the narrow sections 13b arranged at the opposite sides of the longitudinal central axes of the cells (or the data electrodes 2). Since the narrow sections 13b are formed along the lateral surfaces of the partition walls 4, the positional relationship between the outer region 15c of sustaining discharge plasma and the fluorescent layer 5 is improved if compared with that of the known structural arrangement of FIGS. 3A and 3B. Therefore, ultraviolet rays 14 can be effectively irradiated to a large area of the fluorescent layer 5 to improve the luminance of emitted light and the light emitting efficiency. Additionally, the operation load for electrically charging the capacities is reduced because the capacity coupling between the plane electrodes 7c and the data electrodes 2 is small.
However, with the known structural arrangement of FIGS. 4A and 4B, the plane electrodes 7c and the data electrodes 2 overlap each other only in a very small area to consequently reduce the statistic dielectric breakdown paths (dielectric breakdown probability) between them. The net result will be a raised writing voltage and a lowered writing rate. Additionally, the wall charges generated by writing discharges become insufficient to degrade the performance of transition from writing discharges to sustaining discharges. While the performance of transition from writing discharges to sustaining discharges may be improved by raising the writing voltage and/or the sustained voltage, such a measure by turn raises the operating voltage to increase the power consumption rate and the load on the part of the drive circuit. Additionally, error ONs and error OFFs can occur with unselected cells to degrade the quality of the displayed image.
With the known structural arrangement of FIGS. 4A and 4B, the gap between the plane electrodes 7c of transversally adjacent cells is small and hence those cells can give rise to error ONs and error OFFs due to discharge interferences. Thus, the device is forced to operate only with a narrow margin.
If the length L3 of the plane electrodes is increased in an attempt for solving the above problem, new problems including an increase in the inutile capacity coupling, the power consumption rate and the operating load and a reduction in the contrast of the displayed image will occur. If, on the other and, the width W3 of the plane electrodes is reduced, the luminance of emitted light will be reduced.
FIG. 5 is a chart where the performances of the above cited known structural arrangements are rated for comparison. It will be appreciated that each of them has its own advantages and disadvantages and hence is not adapted to solve all the above-identified problems.
The plane electrodes of a PDP disclosed in Japanese Patent Laid-Open Publication No. 2000-156167 are provided with numerous micro-holes formed through them and the effective area of the plane electrodes is reduced by controlling the diameter of the micro-holes and the thickness of the dielectric layer to reduce the discharge current that flows at a rate proportional to the effective area of the plane electrodes in an attempt for solving a problem. The problem is that, when the thickness of the dielectric layer is reduced to lower the discharge start voltage, the discharge current flowing through the plane electrodes increases in a manner as defined by formulas of [electric charge Q=capacity Cxc3x97voltage V] and [capacity C=relative dielectric constant xcex5xc3x97area S/distance d]. In other words, the discharge current that flows at a rate proportional to the effective area of the plane electrodes is reduced by reducing the effective area of the plane electrodes for releasing electric charges (the area of the plane electrodes except the holes) without changing the area of the plane electrodes (as defined by the outer peripheral edges) that affects the discharge spaces and defines the discharge regions.
However, while the known technology disclosed in the above cited publication may be effective for reducing the discharge current, it does not go any further and hence is insufficient for highly efficiently generating plasma in the discharge spaces and thoroughly expanding the generated plasma.
It is an object of the present invention to provide an AC plane discharge type plasma display panel that operates reliably for electric discharges with a low power consumption rate and is adapted to satisfactorily expand plasma in the discharge spaces and display high quality images.
An alternating current plane discharge type plasma display panel according to the present invention comprises a front substrate having a plurality of pairs of scan electrodes and common electrodes arranged in a horizontal direction, and a back substrate disposed to face said plane electrodes and having a plurality of vertically extending data electrodes. The scan electrodes and said common electrodes comprise horizontally extending line electrodes and plane electrodes provided for corresponding unit light emitting pixels. The plane electrodes of said scan electrode and said common electrode in each unit light emitting pixel are separated from each other by a discharging gap. Each of said plane electrodes has a first section located close to said discharging gap and a second section located remotely from said discharging gap. The first section has a part overlapping said data electrode as viewed from above and parts extending horizontally from a part overlapping said data electrode. The second section has lateral parts extending vertically along lateral edges of said corresponding data electrode as viewed from above. Partition walls are arranged between said front substrate and said back substrate to form discharge spaces. The partition walls define unit light emitting pixels of red, green and blue. Discharge gas is introduced in said discharge spaces to generate ultraviolet rays.
Thus according to the invention, the profile and the arrangement of the plane electrodes are selected so as to optimize the mode of producing electric discharges and that of expanding plasma in the cells (discharge spaces). Additionally, the positions of the plane electrodes (discharge sections) in the corresponding discharge spaces are selected so as to realize a good balance for the luminance, the light emitting efficiency and the driving characteristics. By appropriately defining the profile and the arrangement of the plane electrodes, discharges can be generated without waste and plasma can be made to expand thoroughly in the discharge spaces for effective emissions of light.
In the AC plane discharge type plasma display panel according to the invention, the first section located close to the discharging gap and the second section located remotely from the discharging gap of each of the plane electrodes may independently have edges that are curved or intersecting each other with an obtuse angle at comers thereof.
Each of the plane electrodes may be connected to the corresponding line electrode at the end part of the second section located opposite to the discharging gap.
The second section of each of the plane electrodes may have (1) a part projecting or extending vertically above the corresponding data electrode from the first section, (2) parts extending in opposite directions from the lateral parts, (3) additionally the extending parts being connected to each other, (4) an inclined part extending in a direction inclined relative to the vertical direction and connecting the lateral parts and a horizontal central part of the first section, (5) an inclined part extending in a direction inclined relative to the vertical direction and connecting the lateral parts and horizontally opposite ends of said first section, (6) a part connecting ends thereof located remotely from the discharging gap, and (7) an inclined part extending in a direction inclined relative to the vertical direction from the lateral parts to the line electrodes so as to come closer. The inclined parts in the case (7) above may be tapered toward the line electrode. Additionally, the inclined parts in the case (7) may be connected to the line electrode at a position overlapping corresponding edges of the date electrode as viewed from above or at a position located at the transversal center of the data electrode.
The line electrodes may be made of a metal material and the plane electrodes may be made of a metal material or a transparent material.
Additionally, a distance between plane electrodes forming said discharging gap may be made to vary continuously or discontinuously in the transversal direction of the plane electrodes.
Both or either of the profile or the area of the first section and that of the second section may be differentiated between the scan electrode and the common electrode.
In the unit light emitting pixels of red, those of green or those of blue, or in one or more unit light emitting pixels, both or either of the profile or the area of the first section and that of the second section may be differentiated between the scan electrode and the common electrode.
In each of the unit light emitting pixels, each of the plane electrodes may be made to overlap the corresponding data electrode at least at two positions along the edges of the plane electrode that are the outer edges of a pattern thereof.
The plasma display panel may further comprise an electrically conductive material connecting at least either said scan electrodes or said common electrodes between the horizontally adjacent unit light emitting pixels. The electrically conductive material may be same as or different from the material of the plane electrodes.
As described above, with the PDP according to the present invention, it is possible to increase the wall charge at the front end of each plane electrode so that the performance of transition from writing discharges to sustaining discharges can be improved to realize a quick transition than ever. As a result, the device can operate with a wide margin to improve the quality of the displayed image.
Additionally, with the PDP according to the present invention, both the convergence of preliminary discharge plasma at the front end of each plane electrode and that of sustaining discharge plasma directed from the plane discharging gap toward the non-discharging gap can be raised to reduce the discharge interferences between adjacent cells than ever. As a result, the device can operate with a wide margin to improve the quality of the displayed image. Additionally, the contrast of the displayed image can be improved.
With the PDP according to the present invention, the degradation of the protection layer and the growth of the electrically conductive light shielding deposit due to local impacts of ions can be alleviated to reduce fluctuations in the operating voltage and the luminance of emitted light than ever. As a result, the panel can enjoy a prolonged service life than ever.
With the PDP according to the present invention, the characteristics of each of the components of the plane electrodes can be controlled by regulating the performance thereof without adversely affecting the luminance of emitted light and the light emitting efficiency. Therefore, any difference in the operating voltage among the cells can be reduced than ever to improve the color temperature and the color purity. As a result, the quality of the displayed image can be improved than ever.
Furthermore, with the PDP according to the present invention, the plane discharging gap is broadened continuously or discontinuously so that the discharges in the narrow gap areas can trigger discharges in the wide gap areas to improve the luminance of emitted light and the light emitting efficiency due to the positive column effect. As a result, the power consumption rate of the panel can be reduced to reduce the degradation of the reliability of the device due to emission of heat.
Moreover, with the PDP according to the present invention, electric discharges can easily take place due to the trigger effect of the edges of the plane electrodes so that writing discharges can be generated quickly with a low voltage than ever. As a result, the panel can operate with a wide margin to improve the quality of the displayed image.
Additionally, with the PDP according to the present invention, the plane electrodes may be made of a metal material instead of a transparent conductive material, which is normally used for conventional plane electrodes, so that the manufacturing yield can be improved at reduced manufacturing cost. As a result, it is possible to provide PDPs at low cost then ever.
Furthermore, with the PDP according to the present invention, the plane electrodes can be electrically connected by means of other than line electrodes (for example, an electrically conductive material same as that of the plane electrodes) to minimize risk of producing broken wires for the electrodes as well as structural defects. As a result, the yield of manufacturing panels can be improved than ever.